1. Field of the Invention
This invention relates generally to computer peripherals, and more particularly, to an orthopedic mouse designed to prevent diseases associated with the use of the computer mouse (e.g. tendinitis, bursitis, and carpal tunnel syndrome).
2. Brief Description of the Prior Art
Computer cursors are generally controlled by a manually manipulated pointing device connected to a computer, such as a mouse, trackball, touch pad, digitizing tablet or the like. The mouse includes a housing that is moved on a flat, stationary surface. The housing contains a motion sensor on its bottom side for tracking movement of the mouse, either as a single button or a plurality of buttons on or near the front edge thereof, and circuitry for electrically communicating with an attached computer. When the mouse is moved on a support surface, the cursor moves in a corresponding direction. When the buttons are pressed, certain actions can be performed, depending on the software application using the mouse. The internal components and electrical and software operations of computer mice are well known in the art.
Typical computer mice, such as the one shown in U.S. Pat. No. D302,426 to Bradley et al., are substantially wider than they are tall, and have generally symmetrical sides so that they can be used by either the right or the left hand. Some mice are specially shaped for providing an optimal fit for a user's right hand. The mouse shown in U.S. Pat. No. D328,597 to Clouss, and sold under the trademark "MouseMan" by Logitech Inc. in Fremont, Calif., has a slightly angled but generally horizontal top surface for supporting the fingers and palm of a right hand. The Microsoft Mouse, Version 2, sold by Microsoft Corporation in Redmond, Wash., includes a concave left side for closely engaging the base of the thumb and palm of a right hand. The mouse shown in U.S. Pat. No. 4,862,165 to Gart includes a surface for supporting some fingers in substantially curled positions. Some ergonomic mice, including the Logitech MouseMan.TM., are also made in left-handed versions.
Most prior art mice have a generally horizontal, primary supporting surface for supporting a hand in a horizontal position, as exemplified by the drawing figures of U.S. Pat. No. 5,157,381 to Cheng, and the drawings in the user's manual of the Microsoft Mouse. However, such prior art mice force the hand, wrist, and forearm to be twisted 80 to 90 degrees out of their natural and relaxed positions, and require constant muscular force to be applied to the hand, wrist, and forearm to maintain their positions. For a three-button mouse, the fore, middle, and ring fingers must be kept in constant tension to prevent them from resting too heavily on the buttons and depressing them inadvertently. A horizontal hand holding a prior art mouse is supported on the desk by only a small area at the wrist on the little finger side, so that a pressure sore may develop thereon. The total effort and discomfort may not seem great at first, but when these mice are used over a prolonged and continuous period of time, users may get diseases associated with the use of the computer mouse (e.g. tendinitis, bursitis, and carpal tunnel syndrome), experience fatigue, discomfort, and even pain in the hand and wrist.
U.S. Pat. No. 5,576,733 discloses an ergonomic computer mouse which includes an upright, primary finger supporting surface for supporting all of the fingers of an upright hand in straight positions in an upright stack. An opposite thumb-supporting surface is provided for supporting the thumb. This arrangement ostensibly provides greater comfort. However, neither the mouse disclosed in the '733 Patent, nor any other existing computer mice will support the hand in the optimal "position of function" (also referred to as the "physiological position") in which the musculature of the hand and forearm are at total rest. Maintaining the hand in a "pincer" position to support both the hand and the forearm in a vertical position requires effort.
A detailed discussion of the "position of function" may be found in, for example, THE HAND, Volume II, Chapter 53, pp.497-501, 1985, published by W. B. Saunders Company, the disclosure of which is hereby incorporated by reference as though fully set forth herein. The position of function relates to the position of the hand at rest, which assumes a certain position. This is largely a mid-position of the range of motion of each and every joint, including the wrist, and rotation of the forearm. The forearm is halfway between pronation and supination. The wrist is in about 20.degree. of dorsiflexion and 10.degree. of ulnar flexion. The fingers are slightly flexed in each of their joints, the index being flexed least and the little finger being flexed the most. The thumb is forward from the hand in partial opposition and its joints are also partially flexed. A more precise description of the position of function can be made with regard to the thumb. In this position, the angle between the first and second metacarpal is about 45.degree.. Each and every "position of function" must endeavor to bring together a number of favorable conditions that are not always compatible with each other. They are those that place the joints in a position in which grasp is easy, in which stiffness is less likely to occur, and, finally, in which eventual stiffness will permit preservation of movements of small aptitude, in a useful range. To that concept we add a concept from the medical field: a position of work used during a prolonged period constitutes a form of immobilization (in function). "There does not exist a `position of function` in immobility; the function of the hand necessarily involves movement." THE HAND, Vol. II, Chapter 53 at 501.